Toughening steel.



UNITED STATES PATENT OFFICE.

SAMUEL S. WALES, OF MUN HALL, IENNSYLMAN IA, ASSIGNOR TO CARNEGIE 'STliIEIi COMPANY, OF PITTSBURG, PENNSYLVANIA, A CORPORATION OF NEW JERSEY.

'roUeHnNINe STEEL.

To all whom it may concern:

Beit known that I, SAMUEL S. WALES, of

Munhall, Allegheny county, Pennsylvania,

have invented a new and useful Improvement in Toughening Steel, of which the fol-' orged, annea ed, then carburized on itsface,

then usually reforged, and then" fibered by the usual process. This plate, in the ordinary practice, is now, toughened by heating it to about 825 degrees C. .It is then quenched in Water or other cooling liquid.

It is then raised to atemperature of 700. or 750 degrees.O., and allowed to cool slowly in order to anneal it. I have found that a great improvement is made in the plate by modifying the last annealing process. After the fibering, I raise theplate to a temperature between775 degrees and 875 degrees (3., preferably to 825 degrees Q. It is then quenched in water, to below 300 degrees C}. I then again heat the plate to a temperature of about 500 to 650 degrees C, prefer ably 550 degrees 0., and again quench it in Water or another cooling liquid. I have found that by this improved method of annealing, I can obtain the same ultimate strength, with an improvement in the elongation and reduction of the metal. I have further found that by thus quenching, and consequently checking the annealing process at exactly the desired point, I can obtain more uniform and positive results. In the Specification of Letters Patent. Application filed November 11, 1907. Serial No. 401,701.

Patented July 20, 1909.

ordinary way the annealing process continues after withdrawal from the furnace,

given by water. Moreover, the higher the' temperature to which the steel is heated, the lar or will be the size of the crystals formed, an by employing water, which allows me to use a lower temperature, I can keep down the size of the grain or crystal and thus ob tain a tougher material.

The process is clearlyapplicable to deck plates which are not carburized, in which case the ste s will be substantially the same as these be ore recited with the carburizing and reforging omitted. It is also applicable to any type of commercialsteel.

Many variations may be made in the ste s of treatment prior to the annealing, without departing from my invention.

I claim z- The method. of toughening steel, consist ing in heating it to a temperature between 775 and 875 degrees 0., chilling the same by water, then heatin the plate to between.

500 and 650 degrees and again quenching by a cooling liquld, substantially as de scribed.

Gnu. B. BLnMINo, R. D. LITTLE. 

